1. Field of the Invention
The invention relates generally to devices and methods used to automatically and evenly spool cable, wire, line or lead rope, and more particularly to such devices and methods used to pull conductors in the electrical utility field.
2. Description of Related Art
Automatic spooling of cable on a drum for conductor pullers is usually done with a self-reversing leadscrew. This is a mechanical means to traverse a spooling head linearly back and forth similar to the manner in which fishing line is spooled on a bait casting reel. The linear speed of the spooling head is proportional to the rotational speed of the drum, where the drum and leadscrew are mechanically linked by a chain. Properly sizing the chain reduction, leadscrew pitch, and leadscrew groove length will spool the cable onto the drum somewhat evenly. However, since the prior art methods are a mechanical solution to proper spooling, all components must be designed, machined and assembled perfectly for it to work correctly. If the cable is not spooled properly, then cable life is decreased due to increased frictional wear and the machine will not work properly. Leadscrews require many parts that are quickly wearable and require frequent maintenance. Furthermore, the leadscrew is typically designed for one specific cable diameter. Therefore, if one cable is exchanged for another, or if the cable shrinks due to stretching, the leadscrew will not work properly, and a new leadscrew system needs to be installed. Also, because of the chain linking the leadscrew to the drum, the leadscrew may not be moved independently of the drum.
Accordingly, what is needed is an improved method and device for automatically spooling cable, wire, line or lead rope on a drum which accomplishes at least the following objectives: (1) automatic cable spooling on the drum with a powered levelwind arm; (2) use of a controller to gauge drum speed and conversion to the appropriate levelwind movement based on the drum flange width and cable diameter; (3) use of a slew bearing and worm gear to support movement of the levelwind arm; (4) use of an encoder in the drum driveline to assist in establishing the proper cable position; and (5) use of an encoder on the worm gear for establishing the actual cable position.